The invention generally relates to axial flow fans for use in automotive cooling applications and, more particularly, to high speed, low torque axial flow fans.
An axial flow fan may be used to produce a flow of cooling air through the heat exchanger components of a vehicle. For example, an airflow generator used in an automotive cooling application may include an axial flow fan for moving cooling air through a liquid-to-air heat exchanger such as an engine radiator, condenser, intercooler, or combination thereof. Often, axial flow fans are driven by electric motors, which, for a given speed, tend to operate most efficiently at low torque. The diameter of an engine cooling fan is often selected based on the radiator size: fans ranging from 250 mm to 600 mm can be used in typical automotive applications. Fans with small diameters (e.g., 300 mm) tend to rotate at higher speeds and at lower torques to obtain the same airflow as a fan with a large diameter (e.g., 500 mm).
Accordingly, there is a need to provide a large axial flow fan configured for operating at high speed yet at low torque to improve module efficiency by allowing the motor driving the fan to operate more efficiently when a small diameter fan cannot be used.
An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing an axial flow fan characterized by operating at high speed and low torque for producing airflow through an engine compartment of a vehicle. The fan includes a hub rotatable about an axis. An annular band is concentric with the hub and spaced radially outward from the hub. A plurality of fan blades are distributed circumferentially around the hub and extend radially from the hub to the annular band. Each blade has substantially the parameters defined by
wherein
r is the non-dimensional radius from the rotational axis, (r=R/Rtip with R being the radius from the rotational axis and Rtip being the radius from the rotational axis at the blade tip),
"xgr" is the stagger angle of the blade at the radial distance R, and
"sgr" is the solidity C/S, with C being chord length and S being the circumferential blade spacing at the radial distance R.
The fan is configured for operating at high speed yet at low torque to improve module efficiency by allowing the motor driving the fan to operate more efficiently when a small diameter fan cannot be used.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.